<b>Platelet-Based Biomarkers: A New Frontier in Inflammation Monitoring for Respiratory Infections</b>

Platelets are essential for haemostasis and have emerging roles in inflammation, particularly in respiratory infections like pulmonary tuberculosis (PTB) and pneumonia. The objective of this study was to assess alterations in platelet counts and indices and their association with ESR in PTB and pneumonia patients compared to healthy controls, in evaluating their diagnostic and prognostic potential. A retrospective case-control study was conducted at a tertiary care center involving 450 participants: 158 PTB patients, 142 pneumonia patients, and 150 healthy controls. Laboratory data including platelet counts, MPV, Pct, PDW, and ESR were retrieved from the hospital’s Laboratory Information System. Receiver Operating Characteristic (ROC) curve analysis using SPSS to determine diagnostic efficacy. PTB and pneumonia patients had significantly higher platelet counts and Pct, and lower MPV compared to controls (p&lt;0.001). In PTB patients, platelet count positively correlated with Pct and ESR, and negatively with MPV and PDW (p&lt;0.001). Similar patterns were observed in pneumonia patients. ROC analysis identified platelet count and Pct cutoff values of 312,500/µl and 0.21%, respectively, with moderate sensitivity and specificity for differentiating PTB from pneumonia. ESR cutoff was 66.5 mm/h with comparable diagnostic performance. Altered platelet counts and indices in PTB and pneumonia patients correlate with ESR levels, suggesting their utility as non-invasive diagnostic and prognostic markers in respiratory infections. Further prospective studies are needed to validate these findings and integrate platelet indices into clinical diagnostics.